ignition? bike ran now wont fire

[bikeguy91]

 Hi, i recently bought an fj, rode it home, but it was rough starting off/at low rpms and was very hard to start. ran great at higher rpms though. now it wont fire at all. i replaced the spark plugs since i was going to do that anyhow, but that didnt change anything. seems like an ignition problem to me. the bike alerady has replacement dyna coils in it from the last guy. does this sound like a coil problem, cdi box, or entirely different realm? thanks

[FJmonkey]

Welcome FNG, have you done anything else to trouble soot the problem? Did you pull the plugs to see if you are getting spark? Are the plugs wet? There are many simple things to check to eliminate possible causes. The rough starting could be from sitting too long and the idle jets clogging up. Very common problem. What year is you FJ? Early years are gravity feed and later years have a fuel pump. That means other things to check that depends on the year. What can we call you besides bikeguy91.

[movenon]

As FJmonkey indicated, more information please  .
"now it won't fire at all" , did you check the ignition fuse and make sure your kill switch is in the run position. Simple things first... Where are you located in the world ?
George

[bikeguy91]

can call me greg. its an 85 fj1100. its getting spark and the plugs aren't wet. all i've really checked is the plugs since it did fire before. once in a while, on a full battery, it will fire for a couple seconds then quit, but only on occasion. this site seemed really helpful for other repairs so i thought i would see if anyone could help before pouring money into it, since i dont have a lot to spend on it. (the $500 electronic ignition systems are out of the question)

located in Massachusetts. yes the kill switch is off and fuses are good.

Thanks

[Flynt]

it will fire for a couple seconds then quit, but only on occasion.

Greg,

When I bought my first FJ it started well on choke, but was rough starting off and at low RPM.  Ran quite well WOT, but I didn't realize how much more was waiting for me.  It sounds to me like you have a more advanced case of clogged carbs than I had.

You should do the most thorough carb cleaning you can and then do it again to make sure they're spotless and totally unplugged, especially the pilot jets and circuits. You might also make sure there's no crap entering the fuel system from the tank.

You're in for a big treat...  keep pressing through the resistance.

Frank

[FJmonkey]

Are the carbs getting fuel? A pinched (improperly routed) fuel line or if the vacuum line to the petcock is cracked it can prevent fuel from flowing.

[bikeguy91]

the lines are routed as pictured on the bike(factory) and the carbs were supposedly "just cleaned" by the guy i bought it from. guess i should check that out for myself.
also the vacuum line is a little frayed at the top. i dont think it would prevent suction, but worth a try. much better than the problems i was thinking i had.
thanks all

[FJmonkey]

If you are going to pull the carbs, check what size pilot jets you have. After putting #40 in, the bike runs better at idle.

[Pat Conlon]

If *all your plugs* are dry, it's fuel related. It would be strange to have all your carbs gum up at once, although many stranger things have happened...

I would look at the the petcock not opening....here's how to check: on your '85 you have 3 settings on your petcock...on...off...and P for prime. Normally your petcock setting should be in the on position.
To test if the problem is with the petcock, turn the petcock lever to the P position and try to start the bike.
See if your plugs are wet. The P position opens the petcock in absence of a vacuum signal so the petcock is open all the time.

Don't leave the petcock in the P position, you can flood your engine, flood your garage floor, etc.
It might be time to invest in a new petcock from RPM.

[FJmonkey]

The new petcock I got from Randy has two positions, PRI and RUN. Run doubles as the OFF position when there is no vacuum.

[Pat Conlon]

Ok good to know, thx Mark 
In this event, turn the petcock to PRI. and see if this gets gas to your plugs.

[movenon]

You are getting good advice here. You are on the FJ learning curve. First as indicated just focus on getting fuel to the carbs. Assume nothing. Your plugs shouldn't be dry. While you are looking at things make sure your choke is functioning at the carbs. Make sure the previous owner did not put a fuel filter in the line. Also when cranking your engine crack open the throttle.

There is more to check but when doing this via the forum without knowledgeable hands and eyeball's at the bike we have to cover the basic things first.  

Sounds like the previous owner was having problems with it and didn't get it sorted out. Its a new to you bike and you will probably have to inspect things closely as you go. I would recommend you get a service manual when you can.

Have patience it is just a machine and it can be sorted out.  My advice is do not tear into the carbs until you understand how they work and how to service them. If you get to that point then go to the files section and read all the carb files, probably more than once.  

George

[jscgdunn]

A few ideas:
As you changed plugs....double check to see if wires are on in right order? Probably are but you never know....

Pull number 1 wire and check to see if you have spark.  As there are two coils I think you might also want to check 3 but I cannot remember exactly.

"Prime" it with a bit of ether or gas...does it fire or run then?


Jeff

[bikeguy91]

thanks guys! im going to take the petcock off and clean it, but i know it was getting gas very recently since the bike drove home a week ago. im thinking clean out the lines and petcock, then carbs and give it a try.

[FJmonkey]

thanks guys! im going to take the petcock off and clean it, but i know it was getting gas very recently since the bike drove home a week ago. im thinking clean out the lines and petcock, then carbs and give it a try.

If you are going to go that far then give your petcock the "suck test" before you remove it. Disconnect the vacuum line at the intake manifold, disconnect one of the fuel lines and have a catch pan/bottle under it to catch the fuel that should come out. Make sure there are no sources of ignition. Suck on the vacuum line. On a good petcock you will be able to suck some air out of the line and then feel it stop, as if the line was pinched off. Fuel will be flowing at this point. Or you will need to keep sucking to keep the fuel flowing due to an air leak in the hose or petcock diaphragm. If enough air is leaking you will have intermittent flow, really bad flow or no fuel flow.  This problem plagued me for a few months before I found it on my 86'. If you have to keep sucking then you need a new petcock, even if fuel is flowing, it will only get worse and strand you someplace far from home. I got a 60 mile ride in a flatbed tow truck back to my house instead of meeting up with some friends for a ride one Sunday.